构造函数中为什么要用this关键字？

package com.lichkin.chot.bean.out.ocLightOn.ct1YieldReport;
import java.util.ArrayList;
import java.util.List;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class Ct1YieldGridBean {
  private String prodId;
  private String prodDsc;
  private String opeId;
  private String prodSize;
  private Integer totalPanelQty = 0;
  private Integer topN;
  private  String qtap; //
  private String qtapDate;
  private String qtapType;
  private String qtapLineId;
  public Ct1YieldGridBean() {
  }
  public Ct1YieldGridBean(String prodId, String prodDsc, String opeId, String prodSize,String qtap ) {
    this.prodId = prodId;
    this.prodDsc = prodDsc;
    this.opeId = opeId;
    this.prodSize = prodSize;
    this.qtap = qtap;
  }
  public Ct1YieldGridBean(String prodId, String prodDsc, String opeId, String prodSize,String qtap,String qtapDate,String qtapType,String qtapLineId ) {
    this.prodId = prodId;
    this.prodDsc = prodDsc;
    this.opeId = opeId;
    this.prodSize = prodSize;
    this.qtap = qtap;
    this.qtapDate = qtapDate;
    this.qtapType = qtapType;
    this.qtapLineId = qtapLineId;
  }

yieldGridDataList.add(new Ct1YieldGridBean(bean.getProdId(), bean.getProdDsc(), bean.getOpeId(), bean.getProdSize(),bean.getLcdLot(),bean.getQtapDate(),bean.getQtapType(),bean.getQtapLineId()));